Reference Guide

Quality of Service 489
DSCP Mapping
When a policer is assigned to a class map (flow), you can specify the action to
take when the amount of traffic in the flow(s) exceeds the QoS-specified
limits. The portion of the traffic that causes the flow to exceed its QoS limit
is referred to as out-of-profile packet
s .
If the exceed action is Remark DSCP (as opposed to Drop), the switch
rewrites the original DSCP value of the out-of-profile IP packets to a new
value, based on the values entered in the DSCP Mapping page. The switch
uses the new values to assign resources and egress queues to these packets.
The switch physically replaces the original DSCP value in the out-of-profile
packets with the new DSCP value.
To use the Remark DSCP exceed action, set the DSCP Out value in the
DSCP Mapping page. Otherwise the action is null, because the DSCP value
in the packet is rewritten to the original DSCP value, set by factory default.
To set new DSCP values:
1
Click Quality of Service > QoS Advanced Mode > DSCP Mapping to
display the
DSCP Mapping page.
2 If the Exceed Action is Out-of-Profile (in the Policy Class Maps page) or
Remark DSCP (in the Aggregate Policy page), the DSCP In values are
rewritten with the
DSCP Out values. Set the DSCP Out values as
required.
Configuring DSCP Mapping Using CLI Commands
The following table summarizes the CLI commands for setting the fields in
the DSCP Mapping page.
Table 22-11. DSCP Mapping CLI Commands
CLI Command Description
qos map policed-dscp dscp-list
to dscp-mark-down
no qos map policed-dscp [dscp-
list]
Configures the policed-DSCP map for
remarking purposes.
Use the no form of this command to
restore the default configuration.